The present invention relates to a fluid velocity measurement system and more particularly, a fluid velocity measurement system with regenerative pulses for readout by counting.
In many applications, especially in industry, the measurement of the velocity of a fluid flowing through a conduit is performed by a mechanical and/or electrical means. Determining fluid velocity by strictly mechanical means, or those means using mechanical movement to some extent, is not the most desirable procedure, since mechanical parts will eventually wear out, bringing about a shutdown of the entire system. A more practical means of measuring fluid velocity is that utilizing strictly electrical means. Some in the past have used electrical means for determining fluid velocity, however, they have always required rather complicated electrical circuitry and were designed to measure velocity under specific conditions. For example, the fluid velocity detector disclosed in U.S. Pat. No. 3,820,393 by R. D. McGunigle, is designed principally for fluid velocity detection in outer space, and that disclosed in U.S. Pat. No. 3,543,578, by R. W. Sampson is principally designed for relatively small fluid rates of fluid flow.
Specifically, the McGunigle patent discloses a velocity measurement system for indicating the time of flight of a fluid carrying signal, which includes means for applying the thermal pulse to the fluid; means for sensing the fluid carrying signal at a downstream tube location and generating an electrical pulse as a signal thereof; means for generating an output voltage signal when the signal pulse is present, a voltage signal having a first polarity when the first electrical pulse has a predetermined polarity and having a polarity opposite the first polarity when the first electrical signal is not of the predetermined polarity. Furthermore, the McGunigle patent discloses means for integrating the output voltage signal and applying the integrated output voltage to a voltage control means to thereby control the duration of the first electrical pulse to effect a known integrated output voltage signal, and means for determining the duration of the first electrical pulse and generating therefrom an informational signal as a function of time of travel of the fluid carried signal from the first location within the tube to the dowstream location.
The Sampson patent discloses a flow meter system including a conduit for the passage of fluid; energy inducing means connected to the conduit; a first set of plural energy sensors spaced along the inner wall of the conduit in a manner to measure the induced energy flow between the first set of sensors; a second set of energy sensors spaced substantially along the axis of the conduit in a manner to measure the induced energy flow between the second set of sensors; a time determining means connected to the first and second sensor sets for determining the respective time for the induced energy flow between the sensors; and a read-out means for representing the rate of flow of the fluid. The Sampson patent is especially complicated by the fact that four sensing elements are required to sense the rate of fluid flow.
Therefore, it is most desirable if an electrical fluid velocity measurement system could be designed which would have a more general application than those taught by the prior art, and yet be more simplified in its operation than those of the prior art. The fluid velocity measurement system of the present invention, unlike the prior art, generates a quotient of the flight time of a heated slug of a fluid divided into a predetermined time.